natural disasters that can happen at any time (and affect lot of people), but has not really happened in while..

would solar flares be considered in the category as in the title?
https://en.wikipedia.org/wiki/Solar_flare

what other events could be in such a category today?
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25112Asked:
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d-glitchCommented:
Earthquakes and tsunamis
Hurricanes and tornadoes
Blizzards, droughts, and monsoons
Meteor impacts

Solar flares, even bad ones, usually affect infrastructure rather humans directly.
d-glitchCommented:
Epidemics like the recent Ebola outbreak might also qualify.

Climate change, natural or man-made, and the associated weather changes and rising sea levels can be catastrophic as well.
Thibault St john Cholmondeley-ffeatherstonehaugh the 2ndCommented:
In the 'develiped' part of the world we are more susceptible to change than we used to be. If something gets into the water supply it can affect whole districts rather than the few hundred using a single well. A power outage isn't  just an inconvenience and having to use candles to find your way to bed, hospitals, transport systems and food supply all rely on power being available. We are very dependant on the things that make our lives comfortable and would suffer seriously if one of them was to fail for any length of time.
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phoffric\Commented:
>> but has not really happened in  while..
I think to get the right answer, you may need to define how much time you intended this to be - a year, a decade, a century, a millennium, a geological epoch?

Consider the time between Earth's magnetic core flipping. During the magnetic core flip transition, there have been articles stating the danger of this event.

Ref: http://www.livescience.com/48333-magnetic-field-flip-within-100-years.html
However, if the magnetic field weakens enough or temporarily disappears during the flip, then the Earth could be hit with dangerous amounts of solar radiation and cosmic rays. The exposure could mean that more people develop cancer, Renne said, though there's no scientific proof this could happen.

NASA doesn't think solar flares would result in a major disaster when an Earth magnetic pole reversal takes place.

Ref: http://www.nasa.gov/topics/earth/features/2012-poleReversal.html
Another doomsday hypothesis about a geomagnetic flip plays up fears about incoming solar activity. This suggestion mistakenly assumes that a pole reversal would momentarily leave Earth without the magnetic field that protects us from solar flares and coronal mass ejections from the sun. But, while Earth's magnetic field can indeed weaken and strengthen over time, there is no indication that it has ever disappeared completely. A weaker field would certainly lead to a small increase in solar radiation on Earth – as well as a beautiful display of aurora at lower latitudes - but nothing deadly. Moreover, even with a weakened magnetic field, Earth's thick atmosphere also offers protection against the sun's incoming particles.

 The science shows that magnetic pole reversal is – in terms of geologic time scales – a common occurrence that happens gradually over millennia. While the conditions that cause polarity reversals are not entirely predictable – the north pole's movement could subtly change direction, for instance – there is nothing in the millions of years of geologic record to suggest that any of the 2012 doomsday scenarios connected to a pole reversal should be taken seriously. A reversal might, however, be good business for magnetic compass manufacturers.

There are indications that even without a Earth magnetic core flip, that a solar storm can affect our lives significantly.

Ref: https://en.wikipedia.org/wiki/Geomagnetic_storm#Satellite_hardware_damage

Electrical devices and satellites

The March 1989 geomagnetic storm caused the collapse of the Hydro-Québec power grid in a matter of seconds as equipment protection relays tripped in a cascading sequence of events.[2][13] Six million people were left without power for nine hours, with significant economic loss.

Satellite hardware damage

Geomagnetic storms and increased solar ultraviolet emission heat Earth's upper atmosphere, causing it to expand. The heated air rises, and the density at the orbit of satellites up to about 1,000 km (621 mi) increases significantly. This results in increased drag on satellites in space, causing them to slow and change orbit slightly. Unless Low Earth Orbit satellites are routinely boosted to higher orbits, they slowly fall, and eventually burn up in Earth's atmosphere.

Skylab is an example of a spacecraft reentering Earth's atmosphere prematurely in 1979 as a result of higher-than-expected solar activity. During the great geomagnetic storm of March 1989, four of the Navy's navigational satellites had to be taken out of service for up to a week, the U.S. Space Command had to post new orbital elements for over 1000 objects affected, and the Solar Maximum Mission satellite fell out of orbit in December the same year.

The vulnerability of the satellites depends on their position as well. The South Atlantic Anomaly is a perilous place for a satellite to pass through.

As technology has allowed spacecraft components to become smaller, their miniaturized systems have become increasingly vulnerable to the more energetic solar particles. These particles can cause physical damage to microchips and can change software commands in satellite-borne computers.[citation needed]

Another problem for satellite operators is differential charging. During geomagnetic storms, the number and energy of electrons and ions increase. When a satellite travels through this energized environment, the charged particles striking the spacecraft cause different portions of the spacecraft to be differentially charged. Eventually, electrical discharges can arc across spacecraft components, harming and possibly disabling them.[citation needed]

Bulk charging (also called deep charging) occurs when energetic particles, primarily electrons, penetrate the outer covering of a satellite and deposit their charge in its internal parts. If sufficient charge accumulates in any one component, it may attempt to neutralize by discharging to other components. This discharge is potentially hazardous to the satellite's electronic systems.[citation needed]
Paul SauvéRetiredCommented:
If you mean in a while, like this weekend, then no.

Typhoons in the pacific this year: Super Typhoon Maysak (final days of March 2015); Typhoon Soudelor made landfall Saturday morning just north of the Taiwanese city of Hualien (August 7 2015)!
ozoCommented:
Asteroid impact
Megacaldera eruption
Gama ray burst
Oceanic Euxinia
viki2000Commented:
tliottaCommented:
Plenty of earthquakes, tsunamis, volcanos (minus super-volcanos fortunately), tornados/hurricanes/typhoons, to keep them from being listed as not happening recently -- depending on the expected time-scale. I'd like to be sure of asteroid/comet encounters, but Russian videos a couple years ago make me unsure how they might or might not be considered. If we include gamma ray bursts, we might as well include rogue planets passing through the solar system, undetected approaching black holes and just about anything else that's normally thought of as "outer space". (Maybe another rapid "inflation" phase of the entire universe? Hey... it apparently happened before.)

But if we stick with good old Earthly natural disasters, I'd think about a massive exposure and melting of some huge oceanic methane hydrates deposit. It's been at least a long time since any previous huge release, and we might be just about due for the next round. (I'm assuming it hasn't already actually started.)

Tom

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25112Author Commented:
Thanks for helping to put in perspective.
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